Wireless communication method, enode b, and user equipment

ABSTRACT

Provided are wireless communication methods, an eNB and a UE. The wireless communication method performed by an eNB includes transmitting downlink control information (DCI) to a user equipment (UE), wherein the DCI is designed based on a coverage enhancement level for the UE.

BACKGROUND 1. Technical Field

The present disclosure relates to the field of wireless communication,and in particular, to wireless communication methods, an eNode B (eNB),and a user equipment (UE).

2. Description of the Related Art

Machine-Type Communication (MTC) is a new type of communication in 3GPPin release 12 and an important revenue stream for operators. Thecoverage enhancement technique is quite useful for some MTC UEs likesensors in the basement which has large loss on signal strength due topenetration loss. For MTC with coverage enhancement, repetition is abasic solution to enhance the coverage.

SUMMARY

One non-limiting and exemplary embodiment provides an approach to designdownlink control information (DCI) for a UE which may need coverageenhancement.

In one general aspect, the techniques disclosed here feature a wirelesscommunication method performed by an eNode B (eNB), including:transmitting downlink control information (DCI) to a user equipment(UE), wherein the DCI is designed based on a coverage enhancement levelfor the UE.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a flowchart of a wireless communicationmethod for an eNB according to an embodiment of the present disclosure;

FIG. 2 schematically illustrates a flowchart of a wireless communicationmethod for a UE according to an embodiment of the present disclosure;

FIG. 3 schematically illustrates a block diagram of an eNB for wirelesscommunication according to an embodiment of the present disclosure; and

FIG. 4 schematically illustrates a block diagram of a UE for wirelesscommunication according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part thereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. It will be readily understood that the aspects ofthe present disclosure can be arranged, substituted, combined, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated and make part of this disclosure.

In the present disclosure, MTC may be taken as an example to describethe principle of the present disclosure; however, it is noted that thewireless communication methods disclosed in the present disclosure cannot only be applied to MTC, but also be applied to other wirelesscommunications such as other communications conforming to LTEspecifications as long as those wireless communications may requirecoverage enhancement (CE). Accordingly, the UEs are not limited to MTCUEs, but can be any other UEs that can perform the communication methodsdescribed in the present disclosure.

For wireless communication with coverage enhancement (for example, 15 dBfor MTC), repetitions of a channel to be transmitted (e.g. PhysicalDownlink Shared Channel (PDSCH) or Physical Uplink Shared Channel(PUSCH)) can be a basic solution to enhance the coverage. The downlinkcontrol information (DCI) for a channel with coverage enhancement mayneed to indicate resource assignment in both time and frequency domains.How to design DCI with relatively small size to for example assignresources for such a channel with coverage enhancement becomes animportant issue of the wireless communication with coverage enhancement.

For example, for a MTC UE, DCI size is quite important as it heavilyimpacts active time of the UE. Active time means the period that theUE's RF/baseband is keeping working status to transmit or receivephysical signals. It reflects the UE's power consumption and is mainlyrelated with repetitions in the time domain. Smaller DCI size can meanthat the UE will use less time to receive the DCI. For example, assumingeach repetition of a small DCI is transmitted by one ECCE (EnhancedControl Channel Element, 36 REs (Resource Element) per ECCE), QPSK(Quadrature Phase Shift Keying), 1/3 coding rate and full occupation ofnarrowband (6 PRBs) are used, and total repetition times are 96, thenthe UE only needs 4 subframes to receive such DCI.

However, assuming one PRB pair transmits each repetition of DCI withlarger size, full occupation of narrowband is used, and total repetitiontimes are 96, then the UE will need 16 subframes to receive such DCI. Soit is meaningful to design DCI with smaller size. Such DCI could also betransmitted by less resource like one ECCE instead of one PRB pair.

Furthermore, one ECCE can only carry 24 bits, which also means it canonly support 8-bit payload size assuming CRC (Cyclic Redundancy Check)uses 16 bits. So DCI payload size requirement is quite tight assumingless resource like one ECCE to transmit DCI. A 1-bit or 2-bit increasewill require more ECCEs for DCI transmission.

In view of the above, how to design DCI with relatively small size forsuch a channel with coverage enhancement is an important issue for thewireless communication with coverage enhancement.

An embodiment of the present disclosure provides a wirelesscommunication method 100 performed by an eNB, as shown in FIG. 1 whichschematically illustrates a flowchart of the wireless communicationmethod 100 according to an embodiment of the present disclosure. Thewireless communication method 100 can include step 101 of transmittingDCI to a UE, wherein the DCI is designed based on a coverage enhancementlevel for the UE.

Situations of UEs with CE may be different due to environment, distanceto the eNB, penetration loss, and so on. Therefore, the wirelesscommunication design may need to consider different coverage enhancementlevels like 5 dB, 10 dB, and 15 dB. Accordingly, the DCI can be designedbased on the coverage enhancement level for the UE. It is noted that, ifany field (for example, a resource assignment field) in the DCI isdesigned based on the coverage enhancement level, the DCI is consideredto be designed based on the coverage enhancement level. For example, asdescribed later in detail, a resource assignment field in DCI containsan index associated with the coverage enhancement level, and thus suchDCI is considered to be designed based on the coverage enhancementlevel.

In an exemplary embodiment, the DCI can use different sizes fordifferent sets of coverage enhancement levels. For example, the coverageenhancement levels can be divided into two sets by comparing thecoverage enhancement levels with a predetermined level. If a coverageenhancement level is larger than the predetermined level, the coverageenhancement level is considered to be a large coverage enhancement leveland is assigned to a large CE level set. If a coverage enhancement levelis smaller than the predetermined level, the coverage enhancement levelis considered to be a small coverage enhancement level and is assignedto a small CE level set. The coverage enhancement level of a UE can beconfigured by the RRC layer, and the predetermined level can bespecified or configured by the RRC layer.

For example, for a small coverage enhancement level, a payload size of26 bits for the DCI can be used; and for a large coverage enhancementlevel, a payload size of 11 bits for the DCI can be used.

Table 1 indicates that two different DCIs (DCI 1 and DCI 2) are designedfor small coverage enhancement levels and large coverage enhancementlevels respectively.

TABLE 1 DCI 2 (large enhancement level) DCI 1 (small coverage Target isto reduce DCI size as enhancement level) much as possible ContentsResource indication (6 bits); Resource indication (6 bits); MCS (5bits); New data indicator (1 bit); New data indicator (1 bit); MCS (2bits); Redundancy version (2 bits); HARQ process number (1 bit); HARQprocess number (3 Antenna port(s), scrambling bits); identity and numberof layers (1 TPC command for PUCCH bit) (2 bits); Antenna port(s),scrambling identity and number of layers (3 bits); SRS request (1 bit);HARQ-ACK resource offset (2 bits) Payload size 26 bits 11 bits

In the example of Table 1, DCI 2 for large CE level has much smallersize since many features like SRS request are not required.

Table 2 indicates that common DCI is designed for both small coverageenhancement levels and large coverage enhancement levels, but the fieldinterpretation is different among different CE levels.

TABLE 2 Common DCI (applied to all CE UEs) Contents Resource indication(6 bits); MCS (5 bits for small coverage enhancement level; 2 bits forlarge coverage enhancement level); New data indicator (1 bit);Redundancy version (2 bits) - such field does not exist for largecoverage enhancement; HARQ process number (3 bits for small coverageenhancement level and 1 bit for large coverage enhancement level); TPCcommand for PUCCH (2 bits for small coverage enhancement level and suchfield does not exist for large coverage enhancement); Antenna port(s),scrambling identity and number of layers (3 bits for small coverageenhancement level and 1 bit for large coverage enhancement); SRS request(1 bit for small coverage enhancement level and such field does notexist for large coverage enhancement); HARQ-ACK resource offset (2 bitsfor small coverage enhancement level and such field does not exist forlarge coverage enhancement) Payload size 26 bits or 11 bits depending onthe coverage enhancement level

As exemplarily shown in Table 1 and Table 2, when the DCI uses differentsizes for different sets of coverage enhancement levels, the DCI for thelarge coverage enhancement levels can use much less bits. It is notedthat the small coverage enhancement level herein also includes the caseof no coverage enhancement.

In addition or alternatively, in an embodiment of the presentdisclosure, the coverage enhancement of a channel (e.g., PUSCH or PUSCH)scheduled by the DCI with the coverage enhancement level can be realizedat least by repetitions in the time domain and/or repetitions in thefrequency domain with a repetition number which represents the totalnumber of repetitions of the channel, and a resource assignment field inthe DCI uses a single index associated with the repetition number tojointly indicate resource assignment in both the time domain and thefrequency domain. This embodiment is another exemplary way of designingthe DCI based on the coverage enhancement level for the UE.

Repetition is an effective way to enhance the coverage of a channel. Therepetition can happen in the time domain, for example, multiplesubframes can be used to transmit a transport block repeatedly. Therepetition can also happen in the frequency domain, for example,multiple PRBs in the frequency domain are used to transport a transportblock. Aggregation in the frequency domain is a way of repetitions inthe frequency domain. Obviously, the repetition can also happen in boththe time domain and the frequency domain. The DCI scheduling a channel(e.g. PUSCH or PDCCH) requiring coverage enhancement may need toindicate resource assignment in both the time domain and the frequencydomain. The resource assignment can be indicated in a resourceassignment field. For example, the resource assignment field may need toindicate how many subframes and how many PRBs in the frequency domainare used for repetition. Optionally, the resource assignment field mayalso need to indicate the resource positions in the frequency domain.The total number of repetitions (the repetition number) can be theproduct of the subframe number in the time domain and the PRB number inthe frequency domain in unit of PRB pair. For example, 100 repetitions(PRB pairs) can be reflected by 2 PRB×50 subframes, that is, therepetition number is 100. Alternatively, the repetition number can alsobe in unit of PRB. For example, 200 repetitions (PRBs) can be reflectedby 2 PRB×100 slots (50 subframes). In the present disclosure, the unitof PRB pair is used to present the repetition number.

An example of resource assignment field design is separate indicationsfor the time domain and the frequency domain. For example, one field isused to indicate the number of subframes in the time domain and anotherfield is used to indicate the number and/or positions of PRBs in thefrequency domain for example within the narrowband (6 PRBs). Table 3illustrates one example of such separate indications.

TABLE 3 Total PRB Number of PRBs pair number Repetitions in in frequency(repetition time domain domain number) 1 1 1 1 2 2 1 3 3 1 4 4 1 5 5 1 66 2 1 2 2 2 4 2 3 6 2 4 8 2 5 10 2 6 12 4 1 4 4 2 8 4 3 12 4 4 16 4 5 204 6 24 Required field size 2 bits 3 bits

In the example of Table 3, 2 bits are used to indicate repetitions inthe time domain and 3 bits are used to indicate repetitions in thefrequency domain. Thus, totally 5 bits are needed for the resourceassignment field. It is noted that, in this example, only PRB number inthe frequency domain is indicated, but the resource position(s) in thefrequency domain is not indicated. The resource position(s) can be forexample configured by the RRC layer or based on identity (ID) of the UE.

Table 4 illustrates another example of separate indications, in whichthe resource position(s) in the frequency domain is indicated.

TABLE 4 Number Total PRB pair Repetitions of PRBs Position in number intime in frequency frequency (repetition domain domain domain number) 1 16 candidates 1 1 2 5 candidates 2 1 3 4 candidates 3 1 4 3 candidates 41 5 2 candidates 5 1 6 1 candidates 6 2 1 6 candidates 2 2 2 5candidates 4 2 3 4 candidates 6 2 4 3 candidates 8 2 5 2 candidates 10 26 1 candidates 12 4 1 6 candidates 4 4 2 5 candidates 8 4 3 4 candidates12 4 4 3 candidates 16 4 5 2 candidates 20 4 6 1 candidates 24 Required2 bits 5 bits field size

In the example of Table 4, 2 bits are used to indicate repetitions inthe time domain and 5 bits are used to indicate repetitions in thefrequency domain. Thus, totally 7 bits are needed for the resourceassignment field.

The benefit of such a separate indication approach as exemplarily shownin Table 3 and Table 4 is flexibility on resource assignment. However,it has the problem that the field size for resource assignment isrelatively large so that the DCI size may be large as well, and the UE'sactive time to for example receive PDSCH is not optimized.

In an embodiment of the present disclosure, a joint indication ofresource assignment is proposed, that is, a resource assignment field inthe DCI uses a single index associated with the repetition number tojointly indicate resource assignment in both the time domain and thefrequency domain. It is noted that one repetition number can correspondto one or more indexes to represent one or more specific resourceassignment ways for the one repetition number. Joint indication mayreduce the field size for resource assignment. For example, in theexample of Table 3, if two more repetition possibilities (for example, 6and 8 repetitions) are added in the time domain, then there needs 3 bitsto indicate 5 possibilities (1, 2, 4, 6 and 8). Therefore, totally 6bits (3 bits for the time domain and 3 bits for the frequency domain)are needed if the separation indication approach is used. However, if ajoint indication is used, then only 5 bits are needed to indicate 30possibilities (5 in the time domain×6 in the frequency domain). One bitis saved. The 5 bits constitute an index associated with the repetitionnumber. Optionally, in this embodiment, transport block size can also bedetermined by the index associated with the repetition number in theresource assignment field. For example, a smaller repetition number canindicate a smaller transport block size, and a larger repetition numbercan indicate a larger transport block size.

In a further embodiment, the same number of repetitions in the timedomain is used for one and the same value of the repetition number. Inother words, only one combination of repetition number in the timedomain and repetition number (number of PRBs) in the frequency domain isused for one repetition number. For example, assuming the repetitionnumber is 8, the resource assignment may be 2 PRBs in the time domain×4subframes in the time domain (simplified as 2 PRBs×4 subframes) or 4PRBs×2 subframe. However, according to this embodiment, for therepetition number of 8, only one possibility of repetition number in thetime domain can be used and the UE knows it in advance. For example, therepetition number in the time domain can be either 4 subframes or 2subframes, and accordingly the repetition number in the frequency domaincan be either 2 PRBs or 4 PRBs. The selection of repetition number inthe time domain or the frequency domain for each repetition number canbe for example configured by the RRC layer or specified in the standard.Therefore, when the UE receives an index corresponding to the repetitionnumber, it can determine the repetition number in the time domain andthe repetition number in the frequency domain. In this way, the size ofthe resource assignment filed can be reduced since only one combinationof repetition number in the time domain and repetition number in thefrequency domain needs to be indicated for one repetition number. Table5 illustrates a specific example of the embodiment that each repetitionnumber only has one combination of repetition number in the time domainand repetition number in the frequency domain in the context of Table 3.

TABLE 5 Total PRB Number of PRBs pair number Repetitions in in frequency(repetition Index time domain domain number) in DCI 1 1 1 0 1 2 2 1 1 33 2 1 4 4 3 1 5 5 4 1 6 6 5 2 4 8 6 2 5 10 7 2 6 12 8 4 4 16 9 4 5 20 104 6 24 11 Required 3 bits field size

In Table 5, each repetition number only has one combination ofrepetition number in the time domain and repetition number in thefrequency domain; therefore, only 3 bits are needed for the resourceassignment field, which saves 2 bits compared with the approach show inTable 3.

Table 6 illustrates another specific example of the embodiment that eachrepetition number only has one combination of repetition number in thetime domain and repetition number in the frequency domain in the contextof Table 4.

TABLE 6 Total Number of PRB pair Repetitions PRBs in Position in numberin time frequency frequency (repetition Index in domain domain domainnumber) DCI 1 1 6 candidates 1 0-5 1 2 5 candidates 2  6-10 1 3 4candidates 3 11-14 1 4 3 candidates 4 15-17 1 5 2 candidates 5 18-19 1 61 candidates 6 20 2 4 3 candidates 8 21-23 2 5 2 candidates 10 24-25 2 61 candidates 12 26 4 4 3 candidates 16 27-29 4 5 2 candidates 20 30-31 46 1 candidates 24 32 Required 5 bits field size

In Table 6, each repetition number only has one combination ofrepetition number in the time domain and repetition number in thefrequency domain; therefore, only 5 bits are needed for the resourceassignment field, which saves 2 bits compared with the approach show inTable 4.

It is reasonable that each repetition number has only one combination ofrepetition number in the time domain and repetition number in thefrequency domain based on the reason that there is almost no performancedifference between different combinations of repetition number in thetime domain and repetition number in the frequency domain. For example,there is almost no performance difference between 2 PRBs×4 subframes and4 PRB×2 subframe for resource assignment. First, frequency hopping isdisabled within “multiple subframes” to realize symbol-level combiningbased on current 3GPP agreements (refer to “Draft Report of 3GPP TSG RANWG1 #80 v0.2.0”). In other words, the resources should keep the sameposition in the frequency domain within “multiple subframes”. Forexample, the value of “multiple subframes” can be 4. Second, the totalrepetition times are the same, for example, 2 PRBs×4 subframes canrealize 8 repetitions and 4 PRB×2 subframe can also realize 8repetitions. Therefore, the embodiment that each repetition number hasonly one combination of repetition number in the time domain andrepetition number in the frequency domain can reduce the field size ofresource assignment while remaining the performance almost unchanged.

In a further embodiment, the least possible repetitions in the timedomain can be assigned for one and the same value of the repetitionnumber. In other words, repetitions in the time domain should be used asless as possible to reduce the UE's active time and thus reduce the UE'spower consumption. The UE's active time is related to repetition numberin the time domain. The smaller the repetition number in the time domainis, the less the UE's active time is. For example, for the totalrepetition number of 8, the resource assignment of “4 PRBs×2 subframes”should be used assuming narrowband of total 6 PRBs in the frequencydomain according to the embodiment since repetitions of 2 subframes inthe time domain are the least possible repetitions and the UE's activetime is the least in this case. For example, “2 PRBs×4 subframes” hasmore repetitions in the time domain but less repetitions in thefrequency domain, and “4 PRBs×2 subframes” has more repetitions in thefrequency domain but less repetitions in the time domain. Therefore, theUE's active time caused by receptions is larger in the case of “2 PRBs×4subframes” than in the case of “4 PRBs×2 subframes”. The UE keeps activefor 4 subframes in the case of “2 PRBs×4 subframes” but only needs tokeep active for 2 subframes in the case of “4 PRBs×2 subframes”. Asspecific examples, the embodiment can be applied to Table 5 and Table 6.

In a further embodiment, only a proper subset of all possible resourcepositions in the frequency domain are considered as frequency positioncandidates of the resource assignment for at least one value of therepetition number. In other words, only limited resource candidates (notall possible resource positions) are kept in the frequency domain sincethere is no much scheduling gain within narrowband. In this way, thesize of the resource assignment field can be further reduced. Table 7 isan example of limited resource candidates in the frequency domain in thecontext of Table 6.

TABLE 7 Total Number of PRB pair Repetitions PRBs in Position in numberin time time frequency (repetition Index in domain domain domain number)DCI 1 1 X1, Y1, Z1 1 0-2 1 2 X2, Y2, Z2 2 3-5 1 3 X3, Y3 3 6-7 1 4 X4 48 1 5 X5 5 8 1 6 X6 6 10 2 4 X7 8 11 2 5 X8 10 12 2 6 X9 12 13 4 4 X1016 14 4 5 X11 20 15 4 6 X12 24 16 Required 4 bits field size

In Table 7, for the repetition number 1, only 3 candidates (X1, Y1 andZ1) out of 6 candidates (assuming narrowband) are considered; for therepetition number 2, only 3 candidates (X2, Y2 and Z2) out of 5candidates are considered; and so on. In this example, only 4 bits areneeded and thus 1 bit is further saved compared with Table 6. The set ofresource candidates (i.e., proper subset of all possible resourcepositions) can be configured by the RRC layer or determined based on IDof the UE.

The above embodiments can be used to any uplink channel (e.g. PUSCH) ordownlink channel (e.g. PDSCH) for any enhancement level or repetitionnumber. In an example, the above embodiments are used to a downlinkchannel for a small enhancement level or repetition number. Whether thecoverage enhancement level is large or small can be determined bycomparing it with a predetermined level. The predetermined level can beconfigured by the RRC layer or specified. In some embodiments, thecoverage enhancement level can also be configured by the RRC layer. Itis noted that the above coverage enhancement level also includes thecase of no enhancement, and the repetition number also includes the caseof no repetition. For example, the first lines in Tables 3-7 representno repetition.

In a further embodiment, if the coverage enhancement level is largerthan a predetermined level and the channel scheduled by the DCI is adownlink channel, all possible resources in the frequency domain areassigned in the resource assignment. In other words, if the coverageenhancement level is large, full occupation of the resources (forexample 6 PRBs of narrowband) in the frequency domain can be used in adownlink channel in order to reduce the UE's active time. Table 8illustrates an example of full occupation of frequency resources.

TABLE 8 Repetitions in time Number of PRBs in domain frequency domainIndex in DCI 8 6 0 20 6 1 40 6 2 100 6 3 200 6 4 400 6 5 800 6 6 1000 67 Required field size 3 bits Resource assignment size 6 bits inseparation indications Time domain: 4 bits (time + frequency) Frequencydomain: 2 bits

In Table 8, all 6 PRBs of narrowband are occupied in the time domain,and only 3 bits are needed to indicate resource assignment, which saves3 bits compared with the separate indication approach. In addition,according to this embodiment, the UE's active time can be reduced.

In a further embodiment, if the coverage enhancement level is largerthan a predetermined level and the channel scheduled by the DCI is anuplink channel, only one resource in the frequency domain is assigned inthe resource assignment. One PRB transmission in the frequency domaincan realize the largest power spectral density (PSD) in uplink.Optionally, the one resource in the frequency domain can be configuredby the RRC layer or based on ID of the UE. Alternatively, limitedresource candidates in the frequency domain can be configured for theresource assignment of the one resource. Table 9 illustrates an exampleof one PRB transmission combined with limited resource candidates in thefrequency domain.

TABLE 9 Number of PRBs Position in Repetitions in in frequency frequencytime domain domain domain Index in DCI 8 1 X, Y, Z 0-2 20 1 X, Y, Z 3-540 1 X, Y, Z 6-8 100 1 X, Y, Z  9-11 200 1 X, Y, Z 12-14 400 1 X, Y, Z15-17 800 1 X, Y, Z 18-20 1000 1 X, Y, Z 21-23 Required field 5 bitssize Resource 6 bits assignment Time domain: size in 4 bits separateFrequency indications domain: 2 bits (time + frequency)

In Table 9, one PRB transmission and three resource candidates in thefrequency domain are used in the uplink for each large repetitionnumber. In other words, only repetitions in the time domain havemultiple options, for example 8, 20, 40, 100 and so on. The field sizefor resource assignment is reduced from 6 bits to 5 bits. It is notedthat the set of resource candidates {x, y, z} can be configured by theRRC layer or determined based on ID of the UE.

In an embodiment, the resource assignment field can be interpreted basedon whether the coverage enhancement level is large or small. In otherwords, different sets of coverage enhancement levels can use differentdesigns of the resource assignment field. For example, for a smallcoverage level, the interpretation of the resource assignment field canuse any of Tables 5-7; for a large coverage level, the interpretation ofthe resource assignment field can use Table 8 for downlink and Table 9for uplink. In this example, it assumes that the UE knows the coverageenhancement level in advance in order to determine which table should beused. For example, the UE can know the information by RRC configuration.

In another embodiment, all possible repetition numbers should be coveredin one table in case the UE does not know the coverage enhancement levelfor example during system information block (SIB) acquisition or randomaccess period as it is common information that should be used for allUEs. For example, Table 10 illustrates an exemplary table that containsall possible repetition numbers (from 1 repetition in the time domain to1000 repetitions in the time domain). Therefore, the UE can interpretthe resource assignment field even if it does not know the coverageenhancement level.

TABLE 10 Number of PRBs Position in Repetitions in in frequencyfrequency time domain domain domain Index in DCI 1 1 X1, Y1, Z1 0-2 1 2X2, Y2, Z2 3-5 1 4 Only one 6 candidate in the following 1 6 7 2 4 8 2 69 4 4 10 4 6 11 8 6 12 20 6 13 40 6 14 100 6 15 200 6 16 400 6 17 800 618 1000 6 19 Required field 5 bits size Resource 6 bits assignment Timedomain: 4 size in bits separate Frequency indications domain: 2 bits(time + frequency)

As shown in Table 10, the field size for resource assignment is reducedfrom 6 bits to 5 bits compared with the separate indication approach. Itis noted that Table 10 is only an example of the solution covering allpossible repetition numbers. The technical features described in theother embodiments can also be applied to the solution covering allpossible repetition numbers unless the context indicates otherwise.

According to embodiments of the present disclosure, the DCI size can bereduced. In some embodiments, the active time of the UE can be reducedand/or the PSD can be increased. It is noted that the above embodimentscan be combined unless the context indicates otherwise. For example, theembodiments of different DCI size for different sets of coverageenhancement levels can be combined with any of the other embodiments.

In addition, at the UE side, an embodiment of the present disclosureprovides a wireless communication method 200 performed by a UE, as shownin FIG. 2 which schematically illustrates a flowchart of the wirelesscommunication method 200 according to an embodiment of the presentdisclosure. The wireless communication method includes step 201 ofreceiving downlink control information (DCI) transmitted from an eNB,wherein the DCI is designed based on a coverage enhancement level forthe UE. It is noted that the above descriptions for the wirelesscommunication can also be applied to the wireless communication method100, which will not be repeated here.

Further, embodiments of the present disclosure also provide an eNB and aUE to perform the above described communication methods. FIG. 3schematically illustrates a block diagram of an eNB 300 for wirelesscommunication according to an embodiment of the present disclosure. TheeNB 300 can include a transmitting unit 301 configured to transmitdownlink control information (DCI) to a UE, wherein the DCI is designedbased on a coverage enhancement level for the UE.

The eNB 300 according to the present disclosure may optionally include aCPU (Central Processing Unit) 310 for executing related programs toprocess various data and control operations of respective units in theeNB 300, a ROM (Read Only Memory) 313 for storing various programsrequired for performing various process and control by the CPU 310, aRAM (Random Access Memory) 315 for storing intermediate data temporarilyproduced in the procedure of process and control by the CPU 310, and/ora storage unit 317 for storing various programs, data and so on. Theabove transmitting unit 301, CPU 310, ROM 313, RAM 315 and/or storageunit 317 etc. may be interconnected via data and/or command bus 320 andtransfer signals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one implementation of the disclosure,the functions of the above transmitting unit 301 may be implemented byhardware, and the above CPU 310, ROM 313, RAM 315 and/or storage unit317 may not be necessary. Alternatively, the functions of the abovetransmitting unit 301 may also be implemented by functional software incombination with the above CPU 310, ROM 313, RAM 315 and/or storage unit317 etc.

FIG. 4 schematically illustrates a block diagram of a UE 400 forwireless communication according to an embodiment of the presentdisclosure. The UE 400 can include a receiving unit configured toreceive downlink control information (DCI) transmitted from an eNB,wherein the DCI is designed based on a coverage enhancement level forthe UE.

The UE 400 according to the present disclosure may optionally include aCPU (Central Processing Unit) 410 for executing related programs toprocess various data and control operations of respective units in theUE 400, a ROM (Read Only Memory) 413 for storing various programsrequired for performing various process and control by the CPU 410, aRAM (Random Access Memory) 415 for storing intermediate data temporarilyproduced in the procedure of process and control by the CPU 410, and/ora storage unit 417 for storing various programs, data and so on. Theabove receiving unit 401, CPU 410, ROM 413, RAM 415 and/or storage unit417 etc. may be interconnected via data and/or command bus 420 andtransfer signals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one implementation of the disclosure,the functions of the above receiving unit 401 may be implemented byhardware, and the above CPU 410, ROM 413, RAM 415 and/or storage unit417 may not be necessary. Alternatively, the functions of the abovereceiving unit 401 may also be implemented by functional software incombination with the above CPU 410, ROM 413, RAM 415 and/or storage unit417 etc.

It is noted that the above descriptions for the communication methodscan also be applied to the UE or eNB, which will not be repeated herein.

The present disclosure can be realized by software, hardware, orsoftware in cooperation with hardware. Each functional block used in thedescription of each embodiment described above can be realized by an LSIas an integrated circuit, and each process described in each embodimentmay be controlled by LSI. They may be individually formed as chips, orone chip may be formed so as to include a part or all of the functionalblocks. They may include a data input and output coupled thereto. TheLSI here may be referred to as an IC, a system LSI, a super LSI, or anultra LSI depending on a difference in the degree of integration.However, the technique of implementing an integrated circuit is notlimited to the LSI and may be realized by using a dedicated circuit or ageneral-purpose processor. In addition, a FPGA (Field Programmable GateArray) that can be programmed after the manufacture of the LSI or areconfigurable processor in which the connections and the settings ofcircuits cells disposed inside the LSI can be reconfigured may be used.

It is noted that the present disclosure intends to be variously changedor modified by those skilled in the art based on the descriptionpresented in the specification and known technologies without departingfrom the content and the scope of the present disclosure, and suchchanges and applications fall within the scope that claimed to beprotected. Furthermore, in a range not departing from the content of thedisclosure, the constituent elements of the above-described embodimentsmay be arbitrarily combined.

Embodiments of the present disclosure can at least provide the followingsubject matters.

According to an embodiment of the present disclosure, there is provideda wireless communication method performed by an eNode B (eNB),including:

transmitting downlink control information (DCI) to a user equipment(UE), wherein

the DCI is designed based on a coverage enhancement level for the UE.

In the foregoing wireless communication method,

coverage enhancement of a channel scheduled by the DCI with the coverageenhancement level is realized at least by repetitions in a time domainand/or repetitions in a frequency domain with a repetition number whichrepresents a total number of repetitions of the channel, and

a resource assignment field in the DCI uses a single index associatedwith the repetition number to jointly indicate resource assignment inboth the time domain and the frequency domain.

In the foregoing wireless communication method,

the same number of repetitions in the time domain is used for one andthe same value of the repetition number.

In the foregoing wireless communication method,

the least possible repetitions in the time domain are assigned for oneand the same value of the repetition number.

In the foregoing wireless communication method,

only a proper subset of all possible resource positions in the frequencydomain is considered as frequency position candidates of the resourceassignment for at least one value of the repetition number.

In the foregoing wireless communication method,

if the coverage enhancement level is larger than a predetermined leveland the channel scheduled by the DCI is a downlink channel, all possibleresources in the frequency domain are assigned in the resourceassignment.

In the foregoing wireless communication method,

if the coverage enhancement level is larger than a predetermined leveland the channel scheduled by the DCI is an uplink channel, only oneresource in the frequency domain is assigned in the resource assignment.

In the foregoing wireless communication method,

if the coverage enhancement level is smaller than the predeterminedlevel, the least possible repetitions in the time domain are assignedfor one and the same value of the repetition number.

In the foregoing wireless communication method,

a transport block size is determined by the index associated with therepetition number in the resource assignment field.

In the foregoing wireless communication method,

the DCI uses different sizes for different sets of coverage enhancementlevels.

According to another embodiment of the present disclosure, there isprovided a wireless communication method performed by a user equipment(UE), including:

receiving downlink control information (DCI) transmitted from an eNode B(eNB), wherein

the DCI is designed based on a coverage enhancement level for the UE.

In the foregoing wireless communication method,

coverage enhancement of a channel scheduled by the DCI with the coverageenhancement level is realized at least by repetitions in a time domainand/or repetitions in a frequency domain with a repetition number whichrepresents a total number of repetitions of the channel, and

a resource assignment field in the DCI uses a single index associatedwith the repetition number to jointly indicate resource assignment inboth the time domain and the frequency domain.

According to another embodiment of the present disclosure, there isprovided an eNode B (eNB) for wireless communication, including:

a transmitter that transmits downlink control information (DCI) to auser equipment (UE), wherein

the DCI is designed based on a coverage enhancement level for the UE.

In the foregoing eNB,

coverage enhancement of a channel scheduled by the DCI with the coverageenhancement level is realized at least by repetitions in a time domainand/or repetitions in a frequency domain with a repetition number whichrepresents a total number of repetitions of the channel, and

a resource assignment field in the DCI uses a single index associatedwith the repetition number to jointly indicate resource assignment inboth the time domain and the frequency domain.

According to another embodiment of the present disclosure, there isprovided a user equipment (UE) for wireless communication, including:

a receiver that receives downlink control information (DCI) transmittedfrom an eNode B (eNB), wherein

the DCI is designed based on a coverage enhancement level for the UE.

In addition, embodiments of the present disclosure can also provide anintegrated circuit which includes module(s) for performing the step(s)in the above respective communication methods. Further, embodiments ofthe present disclosure can also provide a computer readable storagemedium having stored thereon a computer program containing a programcode which, when executed on a computing device, performs the step(s) ofthe above respective communication methods.

1-12. (canceled)
 13. A wireless communication method performed by a userequipment (UE), comprising: receiving first downlink control information(DCI) used for a first coverage enhancement (CE) level, the first DCIincluding frequency domain information and time domain information, thefrequency domain information indicating a number of physical resourceblocks (PRBs) from a plurality of candidates for the number of PRBs in afrequency domain within a narrowband which is a part of a bandwidth, andthe time domain information indicating a number of repetitions in a timedomain; and controlling a reception of a physical downlink sharedchannel (PDSCH) by using the number of physical resource blocks (PRBs)and the number of repetitions in the time domain, wherein a number ofbits of the first DCI is smaller than that of second DCI used for asecond CE level, the second CE level being lower than the first CElevel.
 14. The wireless communication method according to claim 13,wherein one of the first CE level and the second CE level is configuredby Radio Resource Control (RRC) layer.
 15. The wireless communicationmethod according to claim 13, wherein the first CE level is used when aCE level is larger than a threshold.
 16. The wireless communicationmethod according to claim 13, wherein one or more contents included inthe first DCI are same as one or more contents included in the secondDCI, the one or more contents included in the first DCI having fewerbits than the one or more contents included in the second DCI.
 17. Thewireless communication method according to claim 13, wherein the secondDCI includes all contents of the first DCI and additional contents. 18.The wireless communication method according to claim 13, wherein thefrequency domain information further indicates a position of the PRBs inthe frequency domain within the narrowband.
 19. The wirelesscommunication method according to claim 13, wherein the narrowband iscomposed of 6 PRBs.
 20. A wireless communication apparatus comprising: areceiver which, in operation, receives first downlink controlinformation (DCI) used for a first coverage enhancement (CE) level, thefirst DCI including frequency domain information and time domaininformation, the frequency domain information indicating a number ofphysical resource blocks (PRBs) from a plurality of candidates for thenumber of PRBs in a frequency domain within a narrowband which is a partof a bandwidth, and the time domain information indicating a number ofrepetitions in a time domain; and circuitry which, in operation,controls a reception of a physical downlink shared channel (PDSCH) byusing the number of physical resource blocks (PRBs) and the number ofrepetitions in the time domain, wherein a number of bits of the firstDCI is smaller than that of second DCI used for a second CE level, thesecond CE level being lower than the first CE level.
 21. The wirelesscommunication apparatus according to claim 20, wherein one of the firstCE level and the second CE level is configured by Radio Resource Control(RRC) layer.
 22. The wireless communication apparatus according to claim20, wherein the first CE level is used when a CE level is larger than athreshold.
 23. The wireless communication apparatus according to claim20, wherein one or more contents included in the first DCI are same asone or more contents included in the second DCI, the one or morecontents included in the first DCI having fewer bits than the one ormore contents included in the second DCI.
 24. The wireless communicationapparatus according to claim 20, wherein the second DCI includes allcontents of the first DCI and additional contents.
 25. The wirelesscommunication apparatus according to claim 20, wherein the frequencydomain information further indicates a position of the PRBs in thefrequency domain within the narrowband.
 26. The wireless communicationapparatus according to claim 20, wherein the narrowband is composed of 6PRBs.